Does Revving Your Engine Warm it Up Faster? Revealed

If you listen to some old-timers, they’ll tell you to rev your engine in the morning to heat it up.

Don’t listen to them!

While this may have been good advice back in the day, times have changed and modern engines don’t do well if you follow this old-school advice.

I personally never rev my engine and this is for good reason.

Does Revving Your Engine Warm it up Faster?

Revving your engine does warm it up faster, but it comes at a cost. If your car’s been standing outside overnight, the engine will be cold and hard to start. Modern fuel injection systems compensate for this by increasing the amount of fuel which can actually damage your engine if you over-rev it.

Consequences of Revving your Engine

This sounds counter-intuitive, but ask any mechanic and they’ll tell you that it is best to start your engine and drive off immediately.

The American Automobile Association (AAA) advises that you allow your car to idle for only the time that it takes to get in and put on your seatbelt, before driving off. They specifically don’t mention anything about revving your engine.

And there is a good reason behind this.

When motor vehicle engines are cold, they are less efficient and burn more oil and fuel. Trying to increase the engine temperature by putting extra strain on the engine is bad for various different reasons.

Why You Shouldn’t Rev Your Engine When It’s Cold

To understand why it is not a good idea to rev your engine when it’s cold, we need to go back to when cars were carburetor-fed rather than fitted with fuel injection.

Why Carburettors Were Replaced

By the 1980s, car engines were changing over to fuel injection.

There were still vehicles with carburetors (some performance models even had two or more), but for reasons of performance and efficiency, car manufacturers started to change over to fuel injection.

Carburetors work by mechanically providing a metered jet of fuel mixed with air to each cylinder.

When you first started a cold engine with a carburetor, you needed to use the manual choke to increase the amount of fuel going to the engine, otherwise, the engine would either not start or would stall.

Unlike today’s high-performance engines, in those days, the compression and oil rings in the pistons were a lot stronger.

To fit a piston with new rings into the engine required a special tool to compress the rings before they would slide down into the engine.

And even then, you needed a lot of force to push the piston head down. This tight fit prevented the engine oil from leaking up into the combustion chamber of each cylinder.

So, if you revved your cold engine to get it hot more quickly, there was less wear and tear on the piston and walls of the cylinder.

The oils used were generally organic, non-synthetic products. They were very thick when cold and as the engine heated up, they became thinner and less viscous.

The thicker, cold oil adhered to the walls of the cylinder better and was less likely to wash off with the extra fuel.

The oil’s lubricating qualities kept wear and tear to a minimum so that by the time the engine was hot and the oil was thinner, less fuel was being used to keep the engine running.

Fuel Injection and Loose-fitting Rings

Modern engines have much looser pistons, compression rings, and oil rings.

You can compress modern rings with your finger and push the piston into the engine block pretty easily.

This was done to increase performance and reduce fuel consumption. However, it also means that the piston rings don’t provide as much resistance to the combustion gasses and oil from moving up and down the cylinder walls.

A cold engine that hasn’t yet had time to expand with the heat of operation, allows excess fuel and oil to pass easily up and down the piston walls.

While this is great for fuel economy and power, it’s not great for wear and tear on the cylinder walls.

Fuel is an Effective Degreaser

When you rev your modern engine, the fuel injectors squirt additional fuel into the cylinders. This extra fuel does not combust completely, especially when the engine is cold.

It then coats the walls of the cylinder, stripping away the oil and causing increased friction. The lubricating layer of oil which is there to protect the moving parts and allow them to move together more easily is missing. While removing this oil causes greater heat, it also causes a lot of extra wear.

So, revving a cold engine will cause it to wear out more quickly and it’s also a waste of fuel. The extra fuel that isn’t burnt when you’re revving will enter the exhaust pipe and from there travel into the catalytic converter.

Wasting Fuel is Bad For The Environment

Catalytic converters are designed to remove contaminants from your exhaust gasses. This results in lower levels of CO² and other greenhouse gases exiting the tailpipe.

The catalytic converter will remove the excess fuel, oil, and other pollutants and only allow the bare minimum to pass through to the environment. This causes the catalytic converter to wear out sooner as it has to work harder.

With additional unburned fuel ending up covering your spark plugs, you’ll end up with more carbon deposits which will cause them to wear out faster too. They’ll work less efficiently, which will reduce performance and increase your gas usage.

In the end, revving your engine is much more costly, resulting in both excessive fuel costs and increased wear and tear. You also end up damaging the environment by introducing more pollutants into the atmosphere.

Frequently Asked Questions About Does Revving Your Engine Warm it up Faster

Conclusion On Does Revving Your Engine Warm it up Faster

While revving your engine will make it heat up faster, the negative consequences of doing so are not worth it. It is far better to get in and start driving almost immediately.

For the first few minutes of your commute, treat the throttle gently, avoiding harsh acceleration or high speeds until the engine has time to heat up properly.